Given a list of non negative integers, arrange them such that they form the largest number.

For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.

Note: The result may be very large, so you need to return a string instead of an integer.

这道题要求，给定一个数组，将数组中的元素连接在一起，组成更大的数，求能组成的最大的数。由于组成的数可能很大，所以结果用字符串返回。

在解题的过程中，我傻缺了两次/(ㄒoㄒ)/~~。第一次，没正确审题，直接统计出所有数字的频率，然后由大到小拼接，没注意到一个数是不可以拆分的！第二次，不说了，说多了都是泪，直接上图，铭记自己的蠢…
vc+jrDm089PaM6OsxMfDtDm+zdOmuMPU2jM0x7DD5qGjytfPyM7S1rG9072ryv3Xqru7zqrX1rf7tK6jrMi7uvPKudPDc3RyY21wxdC2z8G9uPbX1rf7tK61xLTz0KHAtL72tqjLrcewy62686OsuvPAtLeiz9ayu7bUo6zS8s6qscjI5zO6zTMwLKGwMzChscrHtPPT2qGwM6GxtcSjrLWrysehsDMwM6GxscihsDMzMKGx0KGho8v50tS688C0vs3Su9axz93U2rbg1tbH6b/2tcTM1sLb1tChoyA8YnI+CtfuuvO7u8HLuPbLvMK3o6zWsb3Tsci9z8G9uPbK/bK7zazX6brPtcS089Cho6yxyMjnsci9zzO6zTM0tcTPyLrzzrvWw6Osv8nS1NaxvdOxyL3PMzM0us0zNDO1xLTz0KGho8i7uvPTw9XiuPa3vbeottTV+7j2yv3X6b340NDFxdDyo6zX7rrzsNHFxbrD0PK1xMr9xrS909Ta0rvG8L7Nv8nS1MHLoaMgPGJyPgrPwsPmzPnJz7T6wuujujwvcD4KCgoKPHByZSBjbGFzcz0="brush:java;">class Solution { public: string largestNumber(vector &num){ string ans; if (num.size() < 1) return ans; stringstream pre, post; for (int i = 1; i < num.size(); i++){ for (int j = 0; j < i; j++){ pre << num[j]; post << num[i]; if (pre.str() + post.str() < post.str() + pre.str()){ int temp = num[i]; num.erase(num.begin() + i); num.insert(num.begin() + j, temp); pre.str(""); post.str(""); break; } pre.str(""); post.str(""); } } for (int k = 0; k < num.size(); k++){ pre << num[k]; ans += pre.str(); pre.str(""); } return ans[0]=='0'?"0":ans; } };